The bright future of LED lighting

Although sales will continue for as long as inventory remains, worldwide production of incandescent lights (lamps) has mostly been phased out by the push for more energy-efficient lighting and improvements in light-emitting diodes (LEDs) and compact fluorescent lamps (CFLs). Between 2009 and 2015 the price of an LED lamp as bright as a 60-watt incandescent lamp dropped from U.S. $70 to $10. Meanwhile, the efficiency (or efficacy) of LEDs for turning power into light (as measured in lumens per watt) increased, as did their working lifetime, which greatly lowered their effective operating costs. See also: Fluorescent lamp; Illuminance; Illumination; Incandescent lamp; Lamp; Light-emitting diode; Luminous efficacy; Luminous efficiency; Luminous flux

According to the U.S. Energy Information Administration (EIA), the average 60-watt incandescent lamp produces about 16 lumens per watt and has a lifetime of 1000 hours; an equivalently bright CFL produces 67 lumens per watt and lasts 10,000 hours, and an equivalent LED produces about 83 lumens per watt with a lifetime of 30,000 hours. The long-term energy and monetary savings from the shift in lighting technology are consequently huge. Furthermore, the cost of LED lamps is expected to continue to drop and their efficiency and lifetime to improve. The EIA predicts that if LED use predominates by 2027, the lamps could save the country the equivalent of the annual output of 44 1000-megawatt electric power plants. See also: Electric power generation

LEDS have advantages beyond efficiency and cost as well. Like incandescent lamps, LEDs turn on at full brightness instantly; CFSs can take a minute or more to warm up. Unlike incandescent and CFL lamps, LEDs are cool to touch and can be turned on and off repeatedly without shortening their lifespan. LEDs can be tailored to emit specific wavelengths (colors) of light and they offer better light quality than CFLs, with minimal infrared or ultraviolet light output. LEDs do not abruptly burn out but instead become dimmer as they age: The lifetime of an LED is considered to be over when its brightness diminishes by 30 percent. LEDs do not contain mercury, as CFLs do, but should still be recycled at the end of their life because they contain a number of metals, such as copper, nickel, aluminum, lead, and trace amounts of arsenic, that do not belong in landfills. See also: Color; Electromagnetic radiation

At present, outdoor applications of LEDs for lighting streets and roadways, parking lots, garages, and building exteriors is outpacing indoor residential, commercial, and industrial applications, with almost all outdoor lighting expected to be LED by 2025, according to the U.S. Department of Energy (DOE). By 2030, 84 percent of all lighting applications are expected to be LED. See also: LED roadway lighting: the Los Angeles conversion project

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